making nice cuts in styrene etc?

[steveo3002]

im struggling to make neat cuts in thicker stuff , if it takes a few passes with the blade then im not getting a usuable edge and have to sand it flat

any tools i should be using , i have good scalpel blades etc but theyre not man enough to cut in one pass , dremel wheel melts it

just want a neat off the shelf cut

[steveo3002]

well yeah ive done that too , but then the snapped edge isnt mint